SYNTHESIS OF CARBON EMD COMPOSITE FROM CARBON-SUSPENDED SULFURIC-ACID AND MANGANESE SULFATE BATH

A study has been made of the electrodeposition of MnO2 on a titanium anode from a carbon or carbon/MnO2 composite suspended in a H2SO4-MnSO4 bath. Electrolytic manganese dioxide (EMD) containing acetylene black or vapour-grown carbon fibre shows excellent alkaline battery performance and good grindability. Nevertheless, passivation of the titanium anode sometimes occurs during electrolysis at a current density of 1 A dm-2. This problem is successfully resolved without loss of battery performance, by using carbon/delta-MnO2 as suspension particles. Apart from producing EMDs with good grindability and excellent battery performance, this bath has several other advantages, namely: easy maintenance of the dispersion; good reproducibility; low anode potential during electrolysis, and higher carbon content. It is proposed that a close relationship exists between battery performance and the surface characteristics of EMDs such as BET surface area and pore size.